The fans functionality, as you detail above, is a viable idea. Imagine a BP network of emerging artists. As you mentioned, it may not be appropriate to ask a favorite artist to add you as a friend but it would be easy enough for you to tell that artist, “I love what you do, keep it up!”
I see this idea as part of a larger necessity–mainly being able to provide members with a way to more accurately describe their relationships. Whether a true friend, a fan, a business partner, an intimate partner, a work colleague, a student, a professor, and many others, the ability to describe the type of relationship would add more power to the BP platform.
After all, I have many friends on the testbp.org site but I’ve never met them, I don’t know what most of them look like, and have never talked to them before. Are all of these really my friends? Whether or not they become actual friends in the future is not the issue. The issue is, what is the nature of our relationship at this point in time.